Pin placement holder for surgical pin driver

ABSTRACT

A surgical device for pin insertion in a bone of a subject to aid in performing a bone cutting procedure is provided that includes a drive portion configured to drive a pin for insertion into the bone. The drive portion has a pin drive assembly with a shaft having a shaft proximal end. At least one magnet is associated with the shaft proximal end adapted for attraction and retention of the pin in the shaft proximal end. A spindle assembly is adapted to drive the shaft so as to rotate the pin into the bone to a degree of bone retention that overcomes the attraction and the retention of the pin in the shaft proximal end. An alignment system for surgical bone cutting procedures inclusive of the same is also provided along with a method for aligning a cutting guide on a subject&#39;s bone.

RELATED APPLICATIONS

This application claim is a continuation of U.S. application Ser. No.16/336,370 filed 25 Mar. 2019, now U.S. Pat. No. 11,207,114, issued 28Dec. 2021, that in turn is a US national phase filing of WIPOApplication Serial Number PCT/US2017/053252 filed 25 Sep. 2017 that inturn claims priority benefit of U.S. Provisional Application Ser. No.62/399,634 filed 26 Sep. 2016; the contents of the aforementioned arehereby incorporated by reference.

TECHNICAL FIELD

The present invention generally relates to computer assisted surgery,and more specifically to an improved pin placement holder for tools usedfor actively aligning pins in orthopedic surgical applications.

BACKGROUND

Total knee arthroplasty (TKA) is a surgical procedure in which thearticulating surfaces of the knee joint are replaced with prostheticcomponents, or implants. TKA requires the removal of worn or damagedarticular cartilage and bone on the distal femur and proximal tibia. Theremoved cartilage and bone is then replaced with synthetic implants,typically formed of metal or plastic, to create new joint surfaces.

The position and orientation (POSE) of the removed bone, referred to asbone cuts or resected bone, determines the final placement of theimplants within the joint. Generally, surgeons plan and create the bonecuts so the final placement of the implants restores the mechanical axisor kinematics of the patient's leg while preserving the balance of thesurrounding knee ligaments. Even small implant alignment errors outsideof clinically acceptable ranges correlate to significantly worseoutcomes and increased rates of revision surgery. In TKA, creating thebone cuts to correctly align the implants is especially difficultbecause the femur requires at least five planar bone cuts to receive thefemoral prosthesis. The planar cuts must be aligned in at least fivedegrees of freedom to ensure a proper orientation: anterior-posteriortranslation, proximal-distal translation, external-internal rotation,varus-valgus rotation, and flexion-extension rotation. Any misalignmentin any one of the planar cuts or orientations may have drasticconsequences on the final result of the procedure and the wear patternof the implant.

Cutting guides, also referred to as cutting blocks or cutting jigs, arecommonly used to aid in creating the bone cuts. The cutting guidesinclude guide slots to restrict or align a bone removal device, such asan oscillating saw, in the correct bone resection plane. Cutting guidesare advantageous for several reasons. For one, the guide slots stabilizethe bone removal device during cutting to ensure the bone removal devicedoes not deflect from the desired plane. Additionally, a single cuttingguide may contain multiple guide slots to accurately align and resecttwo or more cutting places, such as a 4-in-1 cutting block. Finally, theguide slots and the working end of the oscillating saw are typicallyplanar in shape, which make them ideal for creating planar bone cuts.The advantages of using a cutting guide are apparent, however, thecutting guide still needs to be accurately positioned on to the boneprior to executing the cut. In fact, it is the placement of the guideslots on the bone that remains one of the most difficult, tedious andcritical tasks for surgeons during TKA.

FIGS. 1A and 1B illustrate perspective views of a distal cutting guide10 disclosed in U.S. Prov. App. No. 62/259,487 assigned to the assigneeof the present application and incorporated by reference herein in itsentirety. FIG. 1A is a front elevation view of the distal cutting guide10 and FIG. 1B is a perspective view thereof. In general, cutting guides10 and alignment guides used herein are made of a rigid or semi-rigidmaterial, such as stainless steel, aluminum, titanium,polyetheretherketone (PEEK), polyphenylsulfone, acrylonitrile butadienestyrene (ABS), and the like. The distal cutting guide 10 includes aguide portion 12 and an attachment portion 14. The guide portion 12includes a guide slot 16 and a bottom surface 20. The guide slot 16 isfor guiding a surgical saw in creating the planned distal cut CP (seeFIG. 1D) on the femur F. The bottom surface 20 may abut against one ormore bone pins P that are placed on the femur F as shown in FIG. 1C. Theattachment portion 14 and the guide portion 12 clamp to the bone pins Pusing fasteners 18. Here, the virtual pin plane PP for the distal cutguide 10 is defined in a surgical plan by planning software using thePOSE of the planned distal cut plane CP (shown in FIG. 1D), and thedistance between the guide slot 16 and the bottom surface 20 of theguide portion 12. The planning software may also use the known width ofthe bone pins P. For example, the pin plane PP may be defined byproximally translating the planned distal cut plane CP by the distancebetween the guide slot 16 and the bottom surface 20 of the distalcutting guide 10. The software may further proximally translate theplanned distal cut plane CP by an additional half width of the pins P.Therefore, when the cutting guide 10 is clamped to the bone pins P asshown in FIG. 1D, the guide slot 16 is aligned with the planned distalcut plane CP.

U.S. Provisional Patent application 62/259,487 also describes a systemand method for aligning a cutting guide on the bone. The system utilizesa dynamic two degree-of-freedom (DOF) hand-held articulating device anda patient specific surgical plan to accurately align one or more pins onto the bone. A cutting guide with one or more guide slots is assembledto the pins where the final POSE of the guide slot(s) correspond withthe POSE of the desired bone cuts. Although the 2-DOF hand-held systemmay accurately align the pins, one design challenge was determining howto removably secure the pin to the articulating device and maintain therotational concentricity of the pin during operation. A simple approachwas to use a standard 3 jaw chuck, or a collet system to hold and securethe pin to the driving tool. The problem with the 3 jaw chuck or colletfor securing a pin is that they require the use of both hands of thesurgeon or involvement of a surgical assistant. One hand to insert thepin, and the second hand to close the chuck or the collet. This processthat relies on use of both hands by the surgeon or involvement of anassistant may be a source of distraction and, is prone to theintroduction of errors in the pin alignment, and surgeon fatigue.

Thus, there is a need for a system and method to accurately align andinsert one or more pins in the bone using a pin driving device that doesnot require both of the surgeon or operator's hands to load a pin intothe device and release the pin from the device once the pin is insertedin the bone. There is a further need for a mechanism and pin holderdesign that maintains the rotational concentricity of the pin whileoperating the device.

SUMMARY OF THE INVENTION

A surgical device for pin insertion in a bone of a subject to aid inperforming a bone cutting procedure is provided that includes a driveportion configured to drive a pin for insertion into the bone. The driveportion has a pin drive assembly with a shaft having a shaft proximalend. At least one magnet is associated with the shaft proximal endadapted for attraction and retention of the pin in the shaft proximalend. A spindle assembly is adapted to drive the shaft so as to rotatethe pin into the bone to a degree of bone retention that overcomes theattraction and the retention of the pin in the shaft proximal end.

An alignment system for surgical bone cutting procedures includes aplurality of bone pins inserted with the surgical device within avirtual plane relative to a cut plane to be created on a subject's bone.A tracking system tracks the position and orientation (POSE) of theworking portion of the surgical device. A cutting guide is configured tobe received on to the plurality of bone pins, with one or more guideslots within the cutting guide being present and configured to guide asurgical saw to make surgical cuts on the subject's bone. A computingsystem is part of the alignment system and programmed to:

-   -   define the virtual plane relative to the cut plane to be created        on the subject's bone;    -   determine a relationship between a location of the working        portion of the surgical device and the virtual plane; and    -   supply a series of commands to the set of components in the        hand-held portion to control pitch and translation to maintain        the pin insertion axis with the virtual plane.

A method for aligning a cutting guide on a subject's bone is alsoprovided in which one or more cut planes from a surgical plan obtainedwith planning software is determined. One or more virtual planesrelative to each of the one or more cut planes to be created on thesubject's bone is also then determined. The aforementioned surgicaldevice is used for aligning and inserting a plurality of bone pinswithin a virtual plane from the one or more virtual planes. A cuttingguide is attached that is configured to clamp on to the plurality ofinserted bone pins and has one or more guides slots configured to guidea surgical saw to make surgical cuts on the subject bone that correspondto the one or more cut planes.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further detailed with respect to the followingdrawings that are intended to show certain aspects of the present ofinvention, but should not be construed as limit on the practice of theinvention, wherein:

FIGS. 1A and 1B illustrate perspective views of a distal cutting guide;

FIG. 1C illustrates a set of pins driven coincident with a virtual pinplane in a femoral bone;

FIG. 1D illustrates the distal cutting guide of FIGS. 1A and 1Bassembled to the pins of FIG. 1C;

FIG. 2 is a perspective view of a drive portion of a hand held endeffector in accordance with embodiments of the invention;

FIG. 3 is a side view of the drive portion of a hand held end effectorshown in FIG. 2 in accordance with embodiments of the invention;

FIG. 4 is a central longitudinal cross-sectional view of FIG. 3 inaccordance with embodiments of the invention;

FIG. 5A is an exploded view of FIG. 3 in accordance with embodiments ofthe invention;

FIG. 5B is an exploded view of FIG. 4 in accordance with embodiments ofthe invention;

FIGS. 6A-6H are detailed individual perspective views of the majorcomponents that form the drive portion of a hand held end effector inaccordance with embodiments of the invention;

FIG. 7A is a detailed side view of the pin drive assembly in accordancewith embodiments of the invention;

FIG. 7B is a detailed exploded and central longitudinal cross-sectionalside view of the pin drive assembly in accordance with embodiments ofthe invention; and

FIG. 8 illustrates a surgical system in the context of an operating room(OR) in accordance with embodiments of the invention.

DETAILED DESCRIPTION

The present invention has utility as a system and method to aid asurgeon in quickly and precisely aligning a guide pin on a bone of asubject, with the aid of a pin placement holder in a pin driverassembly. In contrast to other prior art mechanisms, the presentinvention does not require an operator to use two hands to load andsecure a pin. Certain embodiments of the inventive pin driver assemblyuse a pin guide that aligns an inserted pin to a shaft, where the shafthas a hex socket to rotationally lock the pin to the rotation of theshaft. The shaft also houses two small magnets to attract and secure theinserted pin, the magnets taking the place of a conventional 3-jawchuck, or a collet system to hold and secure the pin to the drivingtool, and thereby eliminate the need for the operator to use both oftheir hands to secure the pin to the driving tool or rely on a secondperson to assist. The magnets pull the inserted pin into the hex socketand prevents the pin from falling out of the pin guide or the hexsocket, the magnet or magnets have a limited Gauss strength balance toretain the pin prior to bone securement, yet release the pin uponsecurement. The operator or surgeon can freely articulate the tool inany angle without worry of the pin falling out of the device.

The system and method is especially advantageous for total kneearthroplasty and revision knee arthroplasty where the position andorientation (POSE) of the pins are used to assemble and align a cuttingguide thereon to facilitate the creation of a desired cut plane.However, it should be appreciated that other medical applications mayexploit the subject matter disclosed herein such as osteotomies and hightibial osteotomies, and the placement of screws for spinal fusions andspinal reconstruction, maxillofacial surgery, fractures, and otherprocedures requiring the precise placement of bone pins, screws, ornails. Similarly, embodiments of the invention described herein may beadapted for use in a non-medical setting wherever the precise placementof a screw, nail, or rivet is needed such as construction, aircraftassembly and carpentry with the proviso that at least a portion of thefasteners are ferromagnetic.

The following description of various embodiments of the invention is notintended to limit the invention to these specific embodiments, butrather to enable any person skilled in the art to make and use thisinvention through exemplary aspects thereof. As used herein, a patient,or synonymously a subject, is defined as a human, a non-human primate;or an animal of a horse, a cow, a sheep, a goat, a cat, a rodent and abird; or a cadaver of any of the aforementioned.

It is to be understood that in instances where a range of values areprovided that the range is intended to encompass not only the end pointvalues of the range but also intermediate values of the range asexplicitly being included within the range and varying by the lastsignificant figure of the range. By way of example, a recited range from1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

Referring now to the figures, FIG. 2 is a perspective view of aninventive drive portion 30 of a hand held surgical device 102, alsoreferred to herein as a pin-driver device (see FIG. 8). FIG. 3 is a sideview of the drive portion 30, while FIG. 4 is a central plane,longitudinal cross-sectional view of FIG. 3. FIG. 5A is an exploded viewof FIG. 3, and FIG. 5B is an exploded view of FIG. 4. FIGS. 6A-6H aredetailed individual perspective views of the major components that formthe drive portion 30. FIG. 7A is a detailed side view of the pin driveassembly 35, and FIG. 7B is a detailed exploded and central longitudinalcross-sectional side view of the pin drive assembly 35. It is noted thatembodiments of the inventive pin driver assembly may also be used withend effectors for robots as well as hand held devices. The drive portion30 has two major subassemblies a spindle assembly 33 and a pin driveassembly 35. The modular design of the spindle 33 allows for thechanging and integration of several different parts. The spindle 33 hasthe following major subcomponents: a bearing cap 42, a bearing holder44, a set of disk springs 58, a coupler 52, a motor holder 48, a motor50, and a spindle cartridge 46. The bearing cap 42 squeezes the outercage of the bearing to facilitate preloading on angular contactbearings. The bearing holder 44 holds an arrangement of bearings 54, andprovides a modular connection to the spindle cartridge 46. The flange 45is perpendicular to the bearing axis to guarantee perpendicularity tothe spindle cartridge 46. It is appreciated that the major subcomponentsof the spindle 33 may be exchanged with minimal effects or changes tothe other parts. For example, the motor holder 48 is readily changed toaccommodate many different size motors and still be capable ofattachment to the spindle cartridge 46. The set of disk springs 58reduce the impact and vibration forces between the bearings 54. Thecoupler 52 attaches the pin driver assembly shaft 38 to the motor shaft51. The motor holder 48 holds the motor 50, provides room for thecoupler 52, and has a flange 49 connection that attaches to the spindlecartridge 46. The flat side of the flange 49 guarantees that the motoraxis is perpendicular to the spindle cartridge wall 47. In addition, theflange 49 has allowance to translationally move the motor axis shaft todecrease radial misalignment between the pin drive shaft 38 and themotor shaft 51.

The spindle cartridge 46 serves as the centerpiece of the spindleassembly 33. The spindle cartridge 46 has two parallel flange walls 47to attach the bearing holder 44, and the motor holder 48 to facilitate acorridor or parallel shafts between the motor 50 and the pin driverassembly 33. The spindle cartridge 46 may also have a mechanism, such asa screw, clasp, or other fastener, to permit a fiducial marker array 32to attach to the drive portion 30. In other embodiments, the fiducialmarker array 32 or individual fiducial markers are an integral part ofthe drive portion 30. A hand-held attachment member 40 connects with thespindle cartridge 46 and is adapted to pivotally attach with thehand-held portion of the hand-held surgical device 102. The fiducialmarkers may be active markers such as light emitting diodes (LEDs),passive markers such as retroreflective spheres, or other trackingreference markers such as magnetic sensors, ultrasonic beacons, inertialmeasuring units, and combinations thereof.

The pin driver assembly 35 is designed to increase surgical usabilityand accuracy. The pin driver assembly 35 has the following majorsubcomponents: a spindle shaft 38, a pin guide 36, and a magnet 56. Thepin driver assembly 35 assembles to the spindle assembly 33 by way ofthe spindle shaft 38, where the spindle shaft 38 runs through thespindle cartridge 46 via the bearing holder 44, and attaches to themotor 50 via the coupler 52. In operation, a surgeon places a pin P intothe pin guide 36. At least one magnet 56, which is fixed in the shaft38, snap a male hex end 64 of the pin P into a hex socket 59 of theshaft 38. In a specific embodiment of the present invention, the magnets56 are adhesively bonded to the shaft 38 in a magnet holder 57 that isproximal to the hex socket 59. The magnet(s) 56 prevent the pin P fromfalling out of the pin guide 36 by keeping a magnetic attractive forceon the magnetically attracted metallic pin P. The pin guide 36 has adistal end 37 and a proximal end 39. The inner diameter of the distalend 37 is tightly dimensioned to the outer diameter of the pin P, andfits over the pin P with a small amount of clearance that constrains thepin's rotational axis to the shaft's rotational axis with a very littleamount of play. The pin guide proximal end 39 has an inner diameterlarger than that of the distal end 37 and is tightly dimensioned to theouter diameter of a distal portion 66 of the shaft 38. The design of thepin guide 36 stabilizes the pin P and makes the pin P rotateconcentrically about the longitudinal axis of the shaft as the motor 50drives (i.e. rotates) the pin P. One may accomplish this stabilizationand alignment by manufacturing the shaft 38 with a deeper hex socket;however there are manufacturing constraints and added costs to do so.Therefore, the pin guide 36 is advantageous from a manufacturing pointof view.

The hex socket 59 on the spindle shaft 38 rotates the pin P, whichcauses the pin P to drill deep inside a subject bone, and the grooves 62on the pin P firmly hold the pin P in place. Once the pin P is firmlyplaced inside the subject bone, the magnetic pull force on the pin P isovercome and the pin P releases from the pin driver assembly 35 as thesurgeon removes the pin driver assembly 35. In a specific inventiveembodiment, the pin P is made of magnetically attractive stainless steeland the pin guide 36 is made of aluminum.

FIG. 8 illustrates an inventive embodiment of a pin driving surgicalsystem 100 in the context of an operating room (OR). The surgical system100 generally includes an articulating surgical device 102 withembodiments of the drive portion 30, a computing system 104, and atracking system 106. The surgical system 100 is able to guide and assista user in accurately placing pins coincident with a virtual plane thatis defined relative to a subject's bone. The virtual plane is defined ina surgical plan such that a cutting guide when assembled to the insertedpins align one or more guide slots with the bone cuts required toreceive a prosthetic implant in a planned position and orientation.

Computing System and Tracking System

The pin-driver device 102 is controlled by commands from the computingsystem 104 to maintain the coincidence of the longitudinal axis of thepin P with a virtual plane defined in the surgical plan. The computingsystem 104 may include a planning computer 108 including a processor; adevice computer 110 including a processor; a tracking computer 112including a processor; and peripheral devices. Processors operate in thecomputing system 104 to perform computations associated with theinventive system and method. It is appreciated that processor functionsare shared between computers, a remote server, a cloud computingfacility, or combinations thereof.

In a particular embodiment, the device computer 110 may include one ormore processors, controllers, and any additional data storage mediumsuch as RAM, ROM or other non-volatile memory to perform functionsrelated to the operation of the surgical device 102. For example, thedevice computer 110 may include software, data, and utilities to controlthe surgical device 102, receive and process tracking data, executeregistration algorithms, execute calibration routines, provide workflowinstructions to the user throughout a surgical procedure, as well as anyother suitable software, data or utilities required to successfullyperform the procedure in accordance with embodiments of the invention.

The planning computer 108, device computer 110, and tracking computer112 may be separate entities as shown, or it is contemplated that theiroperations may be executed on just one or two computers depending on theconfiguration of the surgical system 100. For example, the trackingcomputer 112 may have the operational data to control the device 102without the need for a device computer 110. Or, the device computer 110may include operational data to plan the surgical procedure without theneed for the planning computer 108. In any case, the peripheral devicesallow a user to interface with the surgical system 100 and may include:one or more user-interfaces, such as a display or monitor 114; anduser-input mechanisms, such as a keyboard 116, mouse 118, pendent 120,joystick 122, foot pedal 124, or the monitor 114 may have touchscreencapabilities.

The planning computer 108 contains hardware (e.g., processors,controllers, and memory), software, data and utilities that arededicated to aid a user in planning a surgical procedure, eitherpre-operatively or intra-operatively. This may include reading medicalimaging data, segmenting imaging data, constructing and manipulatingthree-dimensional (3D) virtual models, storing and providingcomputer-aided design (CAD) files, planning the POSE of implantsrelative to the bone, defining virtual pin planes, and generating thesurgical plan data for use with the system 100. The final surgical plandata may include an image data set of the bone, bone registration datapoints, subject identification information, the POSE of the implantsrelative to the bone, the POSE of one or more virtual planes definedrelative to the bone, and any tissue modification instructions. Thefinal surgical plan is readily transferred to the device computer 110and/or tracking computer 112 through a wired or wireless connection inthe operating room (OR); or transferred via a non-transient data storagemedium (e.g., a compact disc (CD), a portable universal serial bus (USB)drive) if the planning computer 108 is located outside the OR.

The device computer 110 contains hardware, software, data and utilitiesthat are primarily dedicated to the operation of the articulating device102. This may include controlling the position and/or orientation (POSE)of the pin P, controlling the speed of the motor 50, the processing ofkinematic and inverse kinematic data of the device 102, the execution ofregistration algorithms, the execution of calibration routines, theexecution of surgical plan data, coordinate transformation processing,providing workflow instructions to the user, and utilizing POSE datafrom the tracking system 106.

The tracking system 106 includes two or more optical receivers 126 todetect the position of fiducial markers. A set of fiducial markersuniquely arranged on a rigid body is referred to herein as a fiducialmarker array (32, 130 a, 130 b). Illustrative examples of the fiducialmarkers may include: an active transmitter, such as an LED orelectromagnetic emitter; a passive reflector, such as a plastic spherewith a retro-reflective film; a distinct pattern or sequence of shapes,lines or other characters. An example of an optical tracking system isdescribed in U.S. Pat. No. 6,061,644. The tracking system 106 may bebuilt into a surgical light 128, located on a boom, a stand, or builtinto the walls or ceilings of the OR. The tracking system computer 112may include tracking hardware, software, data and utilities to determinethe POSE of objects (e.g., bones B, the articulating device 102) in alocal or global coordinate frame. The POSE of the objects is alsoreferred to herein as POSE data, where this POSE data is readilycommunicated to the device computer 110 through a wired or wirelessconnection. Alternatively, the device computer 110 may determine thePOSE data using the position of the fiducial markers detected directlyfrom the optical receivers 126.

The POSE data is determined using the position of the fiducial markers(130 a, 130 b, 130 c) detected from the optical receivers 126 andoperations/processes such as image processing, image filtering,triangulation algorithms, geometric relationship processing,registration algorithms, calibration algorithms, and coordinatetransformation processing. POSE data from the tracking system 106 isused by the computing system 104 to perform various functions. Forexample, the POSE of a digitizer probe 132 with an attached probefiducial marker array 130 b may be calibrated such that the probe tip iscontinuously known as described in U.S. Pat. No. 7,043,961. The POSE ofthe tip or axis of the pin P may be known with respect to a devicefiducial marker array 32 using a calibration method as described in U.S.Prov. Pat. App. 62/128,857. Registration algorithms are readily executedto determine the POSE and/or coordinate transforms between a bone B andthe surgical plan, using the registration methods described in U.S. Pat.Nos. 6,033,415, and 8,287,522. For example, in a registration method,points on a patient bone may be collected from a tracked digitizer probe132 to transform the coordinates of a surgical plan to the coordinatesof the bone.

It should be appreciated that in certain embodiments, other trackingsystems may be incorporated with the surgical system 100 such as anelectromagnetic field tracking system, a mechanical tracking system orother tracking systems that utilize acoustic emitters or reflectors;magnetic emitters or reflectors; accelerometers; gyroscopes; and thelike or any combinations thereof. In particular inventive embodiments,mechanical tracking systems may be used. The replacement of anon-mechanical tracking system with a mechanical tracking system shouldbe apparent to one skilled in the art. In specific embodiments, the useof a mechanical tracking system may be advantageous depending on thetype of surgical system used such as the one described in U.S. Pat. No.6,322,567 assigned to the assignee of the present application andincorporated by reference in its entirety.

Surgical Planning and Execution for a Total Knee Arthroplasty (TKA)Application

The surgical plan is created, either pre-operatively orintra-operatively, by a user using planning software. The planningsoftware may be used to a generate three-dimensional (3-D) models of thesubject's bony anatomy from a computed tomography (CT), magneticresonance imaging (MRI), x-ray, or ultrasound image data set.Alternatively, the surgical plan is created using data collecteddirectly from the patient intraoperatively (e.g. digitized points,kinematic femoral head center, ankle center, statistical bone morphing)such as with typical imageless navigation systems rather than using aper-operative image data set. A set of 3-D computer aided design (CAD)models of the manufacturer's prosthesis are pre-loaded in the softwarethat allows the user to place the components of a desired prosthesis tothe 3-D model of the boney anatomy to designate the best fit, positionand orientation of the implant to the bone.

The surgical plan contains the 3-D model of the patient's operative bonecombined with the location of one or more virtual pin planes. Thelocation of the virtual pin plane(s) is defined by the planning softwareusing the POSE of one or more planned cut planes and one or moredimensions of a cutting guide.

Intra-operatively, the surgical plan is registered to the bone. Thesurgical device 102 then articulates the pin in one-or-more degrees offreedom to align the pin P with a virtual pin plane. Once aligned, theuser may command the device 102, via a trigger, to drive (e.g., rotate)the pin P, while manually advancing the pin P into the bone coincidentwith the virtual pin plane. In some embodiments, the pin P isautomatically advanced into the bone with components associated with thesurgical device 102. The pin P is inserted into the bone to a degree ofbone retention that overcomes the attraction of the pin P to the magnet56. Therefore, the surgical device 102 may be easily removed from thepin P to assemble and install subsequent pins. Cutting guides are thenassembled to the pins to facilitate the creation of the planar cuts thatreceive the knee prosthesis.

Other Embodiments

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of thedescribed embodiments in any way. Rather, the foregoing detaileddescription will provide those skilled in the art with a convenientroadmap for implementing the exemplary embodiment or exemplaryembodiments. It should be understood that various changes may be made inthe function and arrangement of elements without departing from thescope as set forth in the appended claims and the legal equivalentsthereof.

1. A surgical device for inserting a pin into a bone, comprising: adrive portion, comprising: a shaft having a shaft end; a magnetassociated with the shaft end and exerting an attractive force on a pinwhen coupled to the shaft end; and a motor to drive the shaft so as torotate the pin for insertion into the bone to at least a depth where theforce required to pull the pin from the bone is greater than theattractive force exerted on the pin by the magnet.
 2. The device ofclaim 1 wherein the shaft further comprises a socket at the shaft end toaccept a proximal end of the pin.
 3. The device of claim 2 wherein themagnet is situated in the shaft and proximal to the socket.
 4. Thedevice of claim 1 further comprising a pin guide having a first portionwith an inner diameter that fits over a portion of the pin to constraina rotational axis of the pin.
 5. The device of claim 4 wherein the pinguide has a second portion with an inner diameter that fits over aportion of the shaft.
 6. The device of claim 1 further comprising acoupler that couples the shaft to the motor.
 7. The device of claim 1wherein the drive portion further comprises three or more fiducialmarkers to permit a tracking system to track the surgical device.
 8. Thedevice of claim 1 further comprising a hand-held portion movablyconnected to the drive portion.
 9. The device of claim 2 wherein thehand-held portion comprises components to adjust the working portionrelative to the hand-held portion in response to commands from one ormore computers.
 10. A surgical system, comprising: the surgical deviceof claim 1, further comprising a hand-held portion movably connected tothe drive portion; and components for moving the working portionrelative to the hand-held portion; a tracking system to track a positionand orientation (POSE) of the pin when coupled to the shaft end of thesurgical device; and one or more computers to: determine a trackedrelationship between the POSE of the pin and a predetermined location ofa virtual plane, wherein the predetermined location of the virtual planeis defined with respect to a predetermined location for a cut surface tobe created on the bone; and supply commands to the componentscorresponding to movement of at least one of the bone and the hand-heldportion to maintain alignment of an axis of the pin coincident with thevirtual plane.
 11. The system of claim 10 further comprising a pluralityof pins that are inserted coincident with the virtual plane using thesurgical device.
 12. The system of claim 11 further comprising a cuttingguide to be assembled onto the plurality of pins.
 13. The system ofclaim 10 wherein the tracking system is an optical tracking system. 14.The system of claim 10 wherein the one or more computers is a devicecomputer.
 15. The system of claim 14 further comprising a planningcomputer to plan the predetermined location for the cut surface to becreated on the bone.
 16. The system of claim 10 wherein the bone issubject to total knee arthroplasty or revision knee arthroplasty.